1. Field of the Invention
The present invention relates to a zoom camera, and more particularly, to a barrel assembly of a zoom camera in which the structure of a barrel for zooming is improved.
2. Description of the Related Art
A zoom lens of a camera has a lens structure which enables photographing an object at a different magnifying power by changing a focal length within a predetermined range. The lens structure has a front lens group mainly having a positive power and a rear lens group mainly having a negative power. Zooming is achieved as the distance between the front and rear lens groups and the distance between the lens groups and a film surface fixed to a camera body are changed by making these lens groups to move relatively.
In the lens structure with two lens groups like the above case, a front lens frame of the front lens group is installed at a zoom ring and moves by cam coupling or helicoid coupling to a cam barrel having a cam groove. A rear lens frame where the rear lens group is installed is moved along a cam groove formed at the cam barrel. Thus, when the lens groups are moved for zooming from a wide mode to a television mode and vice versa, the interval between the front lens frame and the rear lens frame changes due to backlash so that a photograph taken may be unclear.
On focusing in the above-described zoom lens structure, the backlash is compensated for by moving the front lens group by using a motor installed at a shutter block. However, in the above structure, processing the cam barrel is difficult and the structure of the barrel of a zoom camera is complicated, so that miniaturization of the zoom camera is difficult. Thus, a zoom lens structure is needed in which miniaturization of a zoom camera is possible while maintaining a high magnifying power and a point of inflection is not generated when the lens groups move.
To meet the above needs, it is an object of the present invention to provide a barrel assembly suitable for a zoom camera having a high magnifying power, in which a zoom action is performed by forming a cam at a zoom ring that is a member linearly moving at the tip portion of the barrel, so that an unsmooth zoom action due to the overload to the cam during the zoom action at the point of inflection is prevented.
Accordingly, to achieve the above object, there is provided a barrel assembly of a zoom camera includes a front lens frame where a front lens group is installed, a front guide frame for supporting the front lens frame, a zoom ring advancing and retreating along an optical axis of the front lens group, an inner helicoid ring installed to be capable of advancing and retreating with respect to the zoom ring, a rear lens frame where a rear lens group which is arranged on the same optical axis as the front lens group is installed, and a cam unit formed at the zoom ring and an inner rotator which is installed at the inner helicoid ring to be capable of advancing and retreating, for adjusting the interval between the front lens group and the rear lens group as the front lens group moves.
To achieve the above object, there is provided a barrel assembly of a zoom camera comprising a front lens frame where a front lens group is installed, a front guide frame for supporting the front lens frame, a zoom ring having a cam portion formed along an end portion of the zoom ring, a rear lens frame where a rear lens group arranged on the same optical axis as the front lens group, an inner helicoid ring coupled to the zoom ring by an advancing and retreating unit, an inner rotator advancing and retreating in a lengthwise direction by a guide unit along the inner circumferential surface of the inner helicoid ring, a cam unit, installed at the outer circumferential surface of the inner rotator and the zoom ring, for advancing and retreating the inner rotator during rotation of the inner helicoid ring, and including a coupling unit formed on the inner circumferential surface of the inner rotator and the outer circumferential surface of the rear lens frame, for advancing and retreating the rear lens frame during the rotation of the inner rotator, and an inner guide ring, coupled to the front guide frame and the rear lens frame to be capable of sliding, for preventing the front guide frame and the rear lens frame from rotating.
To achieve the above object, there is provided a barrel assembly of a zoom camera comprising a front lens frame where a front lens group is installed, a front guide frame for supporting the front lens frame, a zoom ring having a cam portion formed along an end portion of the zoom ring, a rear lens frame where a rear lens group arranged on the same optical axis as the front lens group, an inner helicoid ring coupled to the zoom ring by an advancing and retreating unit, an inner rotator advancing and retreating in a lengthwise direction by a first guide unit along the inner circumferential surface of the inner helicoid ring, a cam unit, installed at the outer circumferential surface of the inner rotator and the zoom ring, for advancing and retreating the inner rotator during rotation of the inner helicoid ring, and including a coupling unit formed on the inner circumferential surface of the inner rotator and the outer circumferential surface of the rear lens frame, for advancing and retreating the rear lens frame during the rotation of the inner rotator, and an inner guide ring, coupled to the front guide frame and the rear lens frame to be capable of sliding, for preventing the front guide frame and the rear lens frame from rotating, a guide ring coupled to the inner guide ring to be capable of advancing and retreating by a second guide unit, a helicoid ring in which the guide ring is rotatably inserted and coupled to the inner helicoid ring by a third guide unit, for advancing and retreating the inner helicoid ring while rotating the inner helicoid ring during rotation of the helicoid ring, and a driving unit for driving the helicoid ring.